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This is the value that is assumed to be loading at the instrument MAIN OUT connector. The value is
used to calculate the actual values of amplitude and dc offset. Note that the output impedance of
the instrument MAIN OUT connector is fixed at 50
Ω.
The value may be changed in either of the ways detailed in General: Numeric Editing.
Pressing the
Load
soft-key will alternate between
High-Z
and the last value entered. With
High-Z
selected the load impedance will be assumed infinite.
Range
Pressing the
Range
soft-key will alternate between
Auto
and
Hold
.
The instrument, by default, is in
Auto
mode; it auto-ranges in 10dB attenuator steps (i.e. ‘range’
maximums of 10Vpp, 3.16Vpp, 1Vpp, etc., into 50
Ω
), with the amplitude vernier range limited to
10dB to maintain waveform quality. Selecting
Hold
mode disables auto-ranging; the current
attenuator setting is held and the amplitude vernier range is no longer limited. This can be useful in
eliminating momentary disruptions in the output waveform in Auto mode caused by the switching of
the attenuators while changing the amplitude around an attenuator change point. However,
waveform quality will start to deteriorate when the optimium 10dB operating range of the amplitude
vernier is exceeded.
With range set to
Auto
the amplitude and attenuators will switch automatically and optimal
performance will be realised.
With range set to
Hold
the current attenuator setting will be held while changing amplitude. The
AMP
field in the Parameters Box will show
AttHld
while range is held.
Noise Add
Noise may be added to any output waveform except Square, Pulse and Noise. However, it is
possible to add noise to the arbitrary square-wave found at Arb-
Load
-
BuiltIn2
-
Square.
See
the Continuous Carrier Waveform Operation: Arb Load section for more information on built in arbs.
It is also possible to add noise by using it as the shape parameter in the SUM modulation mode.
